Conventional fibers are useful in a variety of applications including reinforcements, textiles, and acoustical and thermal insulation materials. The fibers can be formed from molten organic materials such as polymers or inorganic materials such as glass. Short, straight fibers typical of conventional thermal and acoustical insulation materials are made by rotary fiberizing techniques and are interconnected by binders. In such techniques, a molten glass material is delivered to a spinner. Fibers produced by the rotating spinner are drawn downwardly towards a conveyor by a blower. As the fibers move downward, binder is sprayed onto the fibers and the fibers are collected into a high loft, continuous blanket on the conveyor. The blanket is passed through a curing oven and the binder is cured to set the blanket to a desired thickness. Because of its combination of thermal, acoustical, and mechanical properties and low cost, rotary fiberglass is the preferred insulation for many applications, including HVAC equipment, water heaters, ranges, and other household appliances where the required thickness is greater than one inch.
In most conventional gas-fired water heaters, the air intake for the combustion chamber and the combustion chamber containing the burner to heat the water tank are located at or near floor level. However, in some circumstances, flammable liquids such as gasoline, kerosene, organic solvent based paint and cleaning supplies may be located near the gas water heater. Vapors from these combustible liquids may accumulate on the floor of the room and some vapors may be drawn into the combustion chamber and ignited by the pilot flame or the flame within the combustion chamber, causing a backflash. The flames could spread outwardly from the water heater and ignite any flammable material within its path. As a result of the occurrences of water heater fires, many safety standards require that the air flow intakes of gas water heaters be located about 18 inches or more above the floor to reduce or prevent the intake of combustible vapors into the combustion chamber.
Specific examples of attempts to raise the air flow intakes above the ground are set forth below.
U.S. Pat. No. 4,940,042 Moore, Jr. et al., which discloses a direct venting system for an indoor water heater that vents the combustion chamber of the water heater directly with the outdoor atmosphere. A conduit assembly extends from an indoor end attached to the water heater (such as to the top) to an outdoor end in communication with the outside atmosphere. The conduit assembly is external to the water heater. The conduit provides continuous combustion air inlet and flue gas outlet plenums to isolate the combustion chamber of the water heater from the indoor room air.
U.S. Pat. No. 5,697,330 to Yetman et al., which. describes a power-vented water heater that includes a draft inducer fan attached to the top end of the storage tank of the water heater via a molded plastic adapter. The molded external plastic adapter has an inlet to receive hot gas from the combustion chamber and cooling external air and an outlet for discharging the received gas. A combustion gas discharge pipe is connected to the fan outlet, and an air intake pipe that has a first portion connected to the outlet leg of the adapter to deliver combustion gas and a second portion coupled to the burner inlet to deliver combustion air along with gaseous fuel.
U.S. Pat. No. 6,058,892 to Haak, II, which describes an air flow control and routing apparatus for attaching to a gas water heater to restrict entry of floor-level gases into the water heater. The air flow control apparatus includes an skirt for surrounding the base of the water heater and an external air intake tube attached to the skirt for transporting inlet air to the combustion chamber. The air intake tube is preferably located at least three feet from the floor, or halfway up the water heater.
U.S. Patent Publication No. 2002/0134322 to Dolan, which describes a safety device for preventing the ignition of flammable vapors by the open flames within a gas fired water heater. In one embodiment of the invention, the combustion chamber is enclosed in a barrier skirt and an external “snorkel” is attached to the side of the water heater such that the air intake is above the floor. The snorkel is preferably 18 inches in length.
Although such prior art systems each have a device or apparatus for moving the air intake above the ground, the systems require additional equipment, such as pipes, fans, adapters, and the like, that are positioned external to the water heater. Not only does such equipment raise the overall cost of the water heater, but it also creates a water heater that requires a larger amount of storage space.
In certain applications, a thinner insulation product is desired or required. In these particular applications, rotary formed fiberglass is typically not used because without expensive modifications to the rotary fiberizing manufacturing line, the rotary fiberglass insulation blanket cannot be controlled to a thickness below one inch. In order to produce an insulation product less than about one inch, and especially less than about ½ inch thick, a more expensive insulation such as flame attenuated or needled E-glass insulation is typically used.
Needle punching, or “needling”, is a method commonly used to bond non-woven, carded, or air-laid blankets without the use of chemical binders. In the needle punching process, barbed needles are passed in and out of the blankets to entangle the fibers. However, needling a carded or air-laid blanket of rotary glass fibers is difficult because the carding or air-laid process breaks the fibers into short lengths that are insufficient for mechanical bonding. As a result, a second type of fiber, such as E-glass, polyester, nylon, or aramid, is conventionally added to the rotary glass fibers. These additional fibers add significant cost to the final product as the second fiber is more expensive than the rotary glass fibers.
Thus, there exists a need in the art for a thin rotary fiberglass insulation product that is inexpensive to manufacture, that can be formed using existing manufacturing lines, and that may be used in applications where a thin insulation is desired.